Hummingbirds love to bathe, but they have a difficult time using bird baths. Traditional bird baths are too deep for them, so they will try to find sources of shallow or misting water. You will find hummingbirds hovering in garden misters, or bathing on leaves that retained water after a rainstorm.
Some gardens have built-in water features that spray water down rocks that have rough edges for their tiny feet to grasp. They will lie on the rocks and let the water come down over them. They have a system like this at the Paton Center for Hummingbirds in Patagonia, Arizona.
THE STUDIO CITY GANG BATHING ON THE DECK
A hummingbird's feathers are critical to its survival, so they spend a lot of time cleaning and maintaining them. Preening is the act of straightening and cleaning feathers with the beak. The hummingbird will reach down to its uropygial gland to gather a bit of secreted oil and then use the tip of the beak to run over all its feathers. They will reconnect the little feather barbules that have become separated and straighten out all their feathers. Preening also removes dirt and any parasites that may be present.
This picture is of a little Violet-crowned Hummingbird busily preening.